Scientists are to look at whether diet affects people's risk of developing an allergy.

Gut bacteria influence how the immune system works, and therefore the risk of developing asthma and allergies, say University of Southampton scientists.

It is just one of the areas to be examined in a £9.8m European investigation into allergy causes.

Around 30% of children and young adults are affected by allergy, and the number is set to rise.

The evidence is that there is going to be a further rise in allergies

Professor Tony Frew, University of Southampton

Around half have a severe allergy which affects their daily livees.

Britain has one of the highest rates of allergy in the world.

In the last 20 years, the rate of eczema and asthma has at least doubled, and there has been at least a threefold increase in nut allergies.

Dietary change

The University of Southampton is one of 25 centres taking part in the Global Allergy and Asthma European Network.

The project, which will be launched later this week, will evaluate research to date and what work still needs to be done to explain why there has been such a significant rise in allergies.

Tony Frew, professor of allergy and respiratory medicine at the university, told BBC News Online: "We'll be aiming to try to make sense of things and see what can be done to prevent further rises in the future."

His team will be looking at how what children eat can affect their risk of developing all allergies - not just those to food.

"We're now eating a very different diet to what we ate in the 1960s," he said.

"It has changed the bacteria that we have in our bowels. They have a very important influence on the immune system."

The immune system controls how the body responds to foreign substances.

It would usually produce antibodies to destroy allergens such as dust mites.

But in some people, allergens trigger inflammation and sometimes hay fever or asthma.

Concern

Professor Frew added: "We are looking at what we are doing wrong and what we can do to change things."

Other researchers across Europe will examine other factors such as why boys are more susceptible to asthma than girls and the effect of pollution.

Professor Frew said: "The evidence is that there is going to be a further rise in allergies. We have not reached a plateau yet.